The Night Fury is the rarest and most intelligent species of dragon. It is small to medium-sized with a sleek, dark body that is almost black with faint lighter patterns similar to that of a manta ray. The Night Fury resembles an axolotl in general appearance and has a pairs of wings, two ear-like appendages on the back of its head to show it's mood, a pair of yellowish-green, cat-like eyes and sharp retractable teeth. Unlike most dragon species, the Night Fury has a short neck and lacks any kind of horns.
In flight, the Night Fury's wingspan is unrivaled, making it resemble some sort of jet plane. This allows it to fly faster, longer and further than any of the other dragon species. It uses the wing-like flaps on its tail to steer and maneuver, similar to an airplane rudder. As seen in the movie, a Night Fury will be incapable of flying if one of these flaps is missing or destroyed.
The Night Fury prefers to eat fish, snagging prey with its sharp pointed teeth. Night Furies can swallow their prey whole and their stomach liquids can easily dissolve the bones of the dragon's food. A Night Fury can also regurgitate its food.
Night Furies are generally quite aggressive to any form of threat they find, similar to how the other dragons treat the Vikings of Berk. According to the Dragon Manual, the Night Fury is considered to be so aggressive that it is likened to the "unholy offspring of lightning and Death itself". Toothless proves himself to be quite an advanced fighter when he manages to defeat a Monstrous Nightmare, one of the Vikings most feared enemies. He also quickly outmaneuvers and defeats Stoic the Vast, who is presumably the best dragon slayer in Berk. Also like it's fellow dragons, Night Furies are seen to have a different personality when they are not threatened. They are curious creatures that attempt to understand new things they observe and are intelligent enough to recreate the actions that they see. This is seen most obviously in Toothless, who attempts to imitate Hiccup when he observes the boy drawing in the ground. Because of their high intelligence, Night Furies are fairly capable of communicating. Toothless does not have a very hard time getting his emotions noticed. Also, he seems to be fairly capable of understanding speech. The best evidence of this is when he makes a noise in agreement with Hiccup regarding the fact the the Red Death can fly. He also seems to understand when Hiccup orders him not to kill his father, Stoic the Vast.
A Night Fury's main type of attack style is dive-bombing at enemies at great speed while being completely camouflaged within the dark sky. The Night Fury is able to be completely invisible at night because of its dark colored scales. In addition of dive-bombing, the Night Fury will also spit out oxygen/acetylene-fueled flames that will explode upon impact and will instantly incinerate anything. Night Furies are picky eaters and will only eat fish. When hunting, a Night Fury uses its sharp retractable teeth as fishing hooks in order to snatch and grip prey from the water. Night Furies are also capable of completely swallowing prey whole and their stomach liquids, which are similar to battery acid, are strong enough to dissolve fish bones. The Night Fury is a very dangerous and elusive dragon and should be avoided at all costs.
Night Fury's are said to be amazing fighters. They use their incredible explosive fire to damage any unlucky foe. They seem to be very agile in flying, using this to confuse their enemies. Also, Toothless can pounce on Vikings. He is also able to fight off Hookfang, a larger Monsterous Nightmare to protect Hiccup.
Apart from its typical dive-bombing attack, a Night Fury's deadly weapon is a blue burst of fire that creates a powerful explosion upon striking a solid surface, or at a certain distance, as evidenced when Hiccup and Toothless are flying, Toothless fires off a celebratory blast that has presumably already exploded when they fly through it. When this attack is used alongside its dark scales and its tendency to never land to steal food during raids, the Night Fury is easily the stealthiest and most dangerous dragon under the cover of night. In fact, before Hiccup knocks Toothless out of the air at the start of the film, none of the Vikings had ever seen or fought a Night Fury and lived to tell the tale. The Night Fury is seen as the most feared dragon of all for good reason.
- The growls and croons of Night Furies and Toothless are a combination of various sounds, including Supervising Sound Designer Randy Thom, elephants, horses, tigers, and even domestic cats.
- Toothless, a Night Fury, is the only dragon in the film adaptation to be given a personal name.